STS-51-D

Discovery launched from Kennedy Space Center on April 12, 1985 at 8:59 AM EST and Landed at Kennedy on April 19 at 8:54 AM EST. The shuttle orbited 110 times at an altitude of 285 nautical miles at an inclination of 28.5 degrees and travelled 2.9 million miles.

The launch set for March 19 was rescheduled to March 28 due to remanifesting of payloads from canceled mission 51-E. The mission was delayed further due to damage to the orbiter’s payload bay door when the facility access platform dropped. The launch on April 12 delayed 55 minutes when a ship entered the restricted solid rocket booster recovery area.

Extensive brake damage and a blown tire during the landing prompted the landing of future flights at Edwards Air Force Base until implementation of the nose wheel steering.

The TELESAT-l (ANIK C-1) communications satellite was deployed attached to the payload assist module (PAM-D) motor. SYNCOM IV-3 (also known as LEASAT-3) was also deployed but the spacecraft sequencer failed to initiate the antenna deployment, spin up and ignition of perigee kick motor. The mission was extended two days to make certain the sequencer start lever was in the proper position.

Griggs and Hoffman performed a space walk to attach Flyswatter devices to the remote manipulator system. Seddon engaged LEASAT lever using the remote manipulator system but the post deployment sequence did not begin. Other payloads were: Continuous Flow Electrophoresis System (CFES) III, flying for sixth time; two Shuttle Student Involvement Program (SSIP) experiments; American Flight Echocardiograph (AFE); two Get Away Specials; Phase Partitioning Experiments (PPE); astronomy photography verification test; medical experiments and toys in space, an informal study of the behavior of simple toys in weightless environment, with results to be made available to school students.